Narcosis – diving deep has a price

Deep diving thailand koh lanta nitrogen narcosis

Nitrogen Narcosis or “raptures of the deep” is an altered mental state caused by the increased pressure of gas in your body. Most divers will start getting affected by this sensation around 30 meters, and the effects will increase by depth.

Most commonly we dive on normal compressed air, comprised by mostly oxygen and nitrogen. Due to the large amount of nitrogen, this gas has the largest impact on narcosis as we descend. The concentration of nitrogen impairs the conduction between our nerve impulses, which resembles the influence of alcohol. As we go deeper the pressure increases, with that the narcosis starts affecting our mental abilities.

Just like drinking small amounts of alcohol, the narcosis itself is not harmful. However, being under the influence 30 meters under the surface can lead to accidents, the same as driving a car intoxicated could. Unlike other drugs the narcosis subsides quite rapidly as the diver ascends, and pressure decreases.

The symptoms of narcosis is the same as anesthetic drugs, causing the diver to feel symptoms like dizziness, euphoria, slowing of reaction time, loss of dexterity, perceptual narrowing, numbness and amnesia.

As the diver continues to dive at this depth he will go through series of different mental states. This includes going from a relaxed, euphoric and overconfident level to a sensation of panic thoughts and terror. This means that a diver, who has experience of making short deep dives, will experience something completely different when staying down there for a period of time.

There is also a general belief that predisposing factors like cold, darkness, clear blue water, sea sickness and hard work underwater has great effect on the severity of the narcosis. A diver, who shows no signs or symptoms on a deep dive one day, can experience narcosis on another.

Divers sometimes believe they are not affected by narcosis after a dive, but this can simply be because the symptoms where disguised by task loading or other factors. Just as a person can think he is not affected by having a couple of drinks. Diving deeper than 30-40 meters will produce some kind of narcosis, the symptoms might not just be as visible.

There are two ways of preventing narcosis. By keeping above 30 meters, you should stay relatively symptom free. The other way is to mix helium, a less narcotic gas, in your cylinder. This will make deep dives more manageable, however mixed gas diving requires some additional training and equipment.

But by managing narcosis, keeping up to date with your training and staying physically fit, you can experience some of the most mystical places on earth.

Start your deep diver course or technical diver training this winter, just ask us!

Book your technical diver training now…

It is time to sign up for this season technical diving courses.  Book your course before the end of August and we will give you last year’s prices.

PADI Tec 40             18,800 baht      (you save 2,200 baht)
PADI Tec 45             18,800 baht      (you save 2,200 baht)
PADI Tec 50             18,800 baht      (you save 4,200 baht)
PADI Sidemount          9,900 baht      (you save 1,000 baht)

Join us in October for our month dedicated for technical diving and receive an extra special price on this package.

Tec 40, 45 & 50        45,000 baht     (you save 7,000 baht)

tectober 2013 technical diving thailand special prices

Do you know your air consumption?

pressure gauge diving thailandWhen you reach 50 bar and you are in the red “zone” then we go up and make a safety stop. Sounds familiar? How much air is this and how much time do I have left underwater? If you want to be in control of the safety aspects of your diving and learn how to figure this out for yourself, keep reading.

Knowing how long our air supply will last us underwater is not just knowledge that technical divers need. It is also very useful for us recreational divers to get an idea of how much air we use and consequently how to plan and execute your dives. Since 50bar is not the same amount of air in an 8 liter cylinder or a 15 liter cylinder, we need to know how to calculate consumption to get an idea of when it is time to stop diving.

In diving we use the term Surface Air Consumption, or SAC for short. We can also use RMV, which is Respiratory Minute Volume; both are calculated in liters/min in the metric system.


By figuring out how much we breathe per minute at the surface we can then use this to calculate how long our cylinder will last us at depth.

First we need to make a dive to get our consumption. This is what you do:

  1. Start with placing yourself at depth, maybe 10 or 15 meters.
  2. Note your time and pressure and then start swimming normally.
  3. After a period of time (eg. 10 min) note your pressure.

After this we are ready to calculate our consumption. Follow my example below:

Let’s say that we use a normal 12 liter cylinder, we dive down to 10 meters and start with 180 bar. After 10 minutes I look at my gauge again and it is now reading 140 bar. What is my SAC?


  1. Determine how much air you used: 180 – 140 bar = 40 bar
    40 bar x 12 liters (cylinder volume) = 480 liters
  2. Divide your used volume by the minutes spent: 480 liters / 10 minutes = 48 liters / min
  3. This is now the air consumption at 10 meters so you will have to bring this to the surface. At 10 meters you have 2 bars of pressure, so all you need to do is divide you consumption at depth with the surrounding pressure: 48 / 2 =  24 liters per minute at the surface.

So can I make a dive to 25 meters for 25 minutes and still have air left for my safety stop?

Let’s find out:

  1. Start with calculating how much air we use on the surface: 24 liters per minute x 25 minutes = 600 liters.
  2. As we are diving to 25 meters we will use 3,5 times the amount: 600 x 3,5 =  2,100 liters
  3. We are using a 12 liter cylinder so the pressure used will be: 2,100 liter / 12 liter = 175 bar
  4. If we start with 200 bar we only have 35 bar left to do our ascent and safety stop with, which means that we should do a shorter or shallower dive to stay conservative.

What is normal?

Normal air consumption for an average diver is between 12 and 20 liters per minute. The more relaxed you dive and the more experience you have you will be able to lower your rate. Very important to know though is that diving in current and exerting yourself can increase your SAC several times.

Niclas Andersson
Assistant Manager
Kon-Tiki Lanta

Kon-Tiki launches PADI Sidemount Diver Course

Learn a new and different way to dive with the PADI Sidemount Diver course!PADI Sidemount diver specialty course thailand

Sidemount is an equipment configuration which has diving cylinders mounted alongside the diver, below the shoulders and along the hips, instead of on the back of the diver. It began as a configuration popular with advanced cave divers, as smaller sections of cave can be penetrated and tanks can be changed with greater ease. The same benefits for operating in confined spaces were also recognized by divers who conducted technical wreck diving penetrations.

Sidemount is now growing in popularity within the technical diving community for general decompression diving and is becoming an increasingly popular specialty training for recreational diving.

PADI Sidemount diving training with proper Side Mount Configuration offers:

  • an alternative way to streamline yourself and the equipment in the water
  • easier cylinder logistics on the surface
  • reduced lower back strain
  • provides redundant gas supply
  • ability to monitor all regulators, valves and gauges because they are in front
  • increased gas supply for longer dives

During the course you will learn:

  • Equipment configuration and preparation
  •  Body posture and trim
  • Propulsion techniques
  • Gas management
  • Proper Sidemount diver procedures and emergencies

Take a new, fun and challenging course on your next holiday to Thailand!

Kon-Tiki launches a new Tec Program

PADI Tec Basics Fundamentals Technical Diving Thailand Koh Lanta

Are you an advanced qualified diver seeking a new challenge on your holiday?

Kon-Tiki is proud to add an additional PADI Specialty to their list of available dive courses. This course is ideal for divers seeking to prepare themselves for Advanced diver training and those who may want to extend their abilities using technical equipment. Along with buoyancy, trim and control in the water we teach you the essential skills for problem solving, gas switching and valve handling using technical diver equipment.

This course doesn’t qualify divers for deeper dives, but it is strongly recommended for all divers wishing to increase skill competency before heading into decompression, cave and wreck diving. The great thing is that you only need to be an advanced qualified diver with 9 dives to start this course.

The course is conducted over 2 days. The first day includes an introduction to the theory behind decompression diving. The second half is a skill workshop explaining the basic philosophy with the technical diving rig and skill practice. Our second day is spent on the boat conducting gas switching, valve drills and problem solving in a real open water environment.

Skills you will learn during the course includes

  • Technical Equipment Set Up
  • Neutral Buoyancy Control & Swimming Techniques
  • Setting Up & Handling Decompression Cylinders
  • Gas Shut Down Drills
  • Free Flowing Regulators
  • Out of Air Situations
  • Bubble Check
  • Saftey Drills
  • NOTOX Gas Switching
  • Calculating Air Consumption
  • Simulation Decompression Stops
  • Lift Bag Deployment
  • Decompression Planning Using Software

Read more here

or e-mail Niclas Andersson our technical diving instructor on Koh Lanta.